The output from showtrans should have been "/hurd/fifo --multiple-readers".
This happens on ext2fs and tmpfs.

ext2fs uses libdiskfs/file-set-trans.c, which recognizes "/hurd/fifo" and converts it to S_IFIFO, but ignores the arguments. In contrast, if it converts "/hurd/symlink" to S_IFLNK, it saves the first argument of the translator as the target of the symlink (and ignores any remaining arguments). I think it should check that it understood everything that was in the arguments, and if not, save the arguments unchanged as if it hadn't recognized the translator.